The invention relates to non-human congenic animals and congenic animal populations that exhibit a type II diabetes-associated phenotype, as well as insulin degradation polypeptides having substitutions that confer type II diabetes-associated phenotypes.
Type II diabetes or non-insulin dependent diabetes mellitus (NIDDM) is an increasing health burden in urbanized societies with aging populations, as the disease is associated with older, physically inactive, overweight individuals. Approximately 135 million people worldwide are affected and therefore are at an increased risk for myocardial infarction, stroke, end-stage kidney disease, vision defects, and neurological problems.
In general, it is considered that the disease results from a combination of impaired insulin action in target tissues and a reduced capacity to secrete insulin from the pancreatic xcex2-cells. Numerous family and twin studies have demonstrated the critical influence of environmental factors as well as a sizable impact of genetic factors for the risk to type II diabetes. Monogenic variants of diabetes with autosomal dominant mode of inheritance (MODY) or mitochondrial inheritance of disease have been described in recent years at the molecular and clinical levels. The common forms of the disease appear, however, to be multifactorial with influence of both polygenic and environmental factors.
The invention is based on the development of congenic animals and congenic animal populations that have a type II diabetes-associated phenotype. Development of congenic animal strains allows susceptibility genes residing within quantitative trait loci (QTLs) to be identified, as well as the pathophysiological implications of such genes to be characterized. As the congenic animals of the invention have a type II diabetes-associated phenotype, genetic fine mapping also can be performed, so that associated genes, such as the variant of an insulin degradation enzyme described herein, can be positionally cloned. Furthermore, physiological characterization of congenic strains and heterozygous backcross animals provides clues to the contribution of a single QTL to the pathophysiology of a complex phenotype. Niddm1 congenic strains of the invention provide specific animal models for mild type II diabetes that will allow pathophysiological mechanisms of the disease to be refined, and provide a tool for screening pharmaceutical agents.
In one aspect, the invention features a non-human congenic animal that includes genetic material of a donor animal and a recipient animal. The congenic animal exhibits a type II diabetes-associated phenotype, wherein less than about one chromosome (e.g., less than about 50 cM, 20 cM, 10 cM, or 5 cM) of the congenic animal""s genome is derived from the donor animal, and wherein the genetic material from the donor is necessary for expression of the type II diabetes-associated phenotype in the congenic animal. The congenic animal can be marker-defined. Substantially all mitochondria of the congenic animal can be derived from either the recipient animal or the donor animal. The type II diabetes-associated phenotype can be selected from the group consisting of elevated postprandial glycemia, hypertension, glucose intolerance, insulin resistance, abnormal insulin secretion, reduced insulin action, increased body weight, dyslipidemia, hyperinsulinemia, impaired lipogenesis, altered glycogen metabolism, altered coagulation atherosclerosis, altered kidney function, altered nerve function, altered eye function, obesity, and inflammation.
The donor animal""s genome can include a Niddm1a genomic interval. The congenic animal""s genome derived from the donor can include a genomic interval selected from the group consisting of Niddm1a, Niddm1b, Niddm1c, Niddm1d, Niddm1e, Niddm1f, Niddm1g, Niddm1h, and Niddm1i. For example, the genomic interval can be a Niddm1e genomic interval. The congenic animal""s genome derived from the donor also can be selected from a genomic interval selected from the group consisting of NiddmC2, NiddmC3, NiddmC5, NiddmC7, NiddmC9A, NiddmC9B, NiddmC10, NiddmC11, NiddmC13, NiddmC18, NiddmC(13+15), and NiddmC(9+13+15).
The invention also features an isolated cell of a congenic animal of the invention as well as a tissue culture derived from a congenic animal of the invention. The cell can be selected from the group consisting of adipocytes, mesangial cells, hepatic cells, pancreatic cells, muscle cells, endothelial cells, and neural cells. The tissue culture can be selected from the group consisting of adipose tissue, mesangial tissue, hepatic tissue, pancreatic tissue, muscle tissue, blood-vessel tissue, and neural tissue.
Congenic animals of the invention can be non-human mammals (e.g., a rodent such as a rat, mouse, or guinea pig, or a swine), insects, or birds. The rodent can be a rat.
The invention also features non-human congenic animal obtained by crossing a first non-human congenic animal with a second non-human congenic animal, wherein the first and second congenic animals have type II diabetes-associated phenotypes. The first and second congenic animals can have distinct metabolic phenotypes and/or have non-overlapping genomic intervals. Such congenic animals are effective for evaluating epistatic interactions between the non-overlapping genomic intervals.
In another aspect, the invention features a non-human congenic animal population that includes a plurality of non-human congenic animals. The congenic animals exhibit a plurality of type II diabetes-associated phenotypes, wherein each congenic animal within the plurality of congenic animals includes genetic material from a donor animal and a recipient animal, wherein about 0.1% to about 50% of each congenic animal""s genome is derived from the donor animal, and wherein the genetic material from the donor is necessary for expression of the type II diabetes-associated phenotype in each congenic animal.
The invention also features a method for testing a pharmaceutically active compound. The method includes administering a test compound to a non-human congenic animal exhibiting a type II diabetes-associated phenotype, wherein the non-human congenic animal includes genetic material of a donor animal and a recipient animal, wherein less than about 50 cM of the congenic animal""s genome is derived from the donor animal, and wherein the genetic material from the donor is necessary for expression of the type II diabetes-associated phenotype in the congenic animal; and evaluating the test compound for an effect on at least one type II diabetes-associated phenotype in the congenic animal. The congenic animal can include the genetic intervals as described above. The animal can include a progeny animal of a cross between two congenic parent animals, the parent animals having distinct congenic intervals.
In another aspect, the invention features a method for testing a pharmaceutically active compound. The method includes administering a test compound to a plurality of non-human congenic animals exhibiting a plurality of type II diabetes-associated phenotypes; and evaluating the test compound for an effect on at least one type II diabetes-associated phenotype, wherein each congenic animal within the plurality of congenic animals includes genetic material from a donor animal and a recipient animal, wherein about 0.1% to about 50% of each congenic animal""s genome is derived from the donor animal, and wherein the genetic material from the donor is necessary for expression of the type II diabetes-associated phenotype in each congenic animal. The plurality of congenic animals can include at least two rats having congenic intervals on different chromosomes.
The invention also features an article of manufacture that includes isolated cells of a non-human congenic animal exhibiting a type II diabetes-associated phenotype. The article further can include a label or package insert indicating the cells are useful for evaluating compounds that may be effective for alleviating type II diabetes-associated phenotypes.
In another aspect, the invention features a method of doing business. The method includes offering for sale a non-human congenic animal exhibiting a type II diabetes-associated phenotype, or a cell derived therefrom; and communicating that the animal is effective for testing or evaluating compounds that are effective for alleviating type II diabetes-associated phenotypes.
In yet another aspect, the invention features a method of making a non-human congenic animal that includes mating a donor animal and a recipient animal to produce a progeny animal; and successively backcrossing the progeny animal with the recipient animal for at least 10 generations to produce the congenic animal, wherein the congenic animal exhibiting a type II diabetes-associated phenotype, wherein less than about 50 cM of the congenic animal""s genome is derived from the donor animal, and wherein the genetic material of the donor is necessary for expression of the type II diabetes-associated phenotype in the congenic animal.
The invention also features an isolated insulin degradation polypeptide and an isolated polynucleotide encoding the insulin degradation polypeptide, wherein the polypeptide includes at least one amino acid substitution, wherein the amino acid substitution is linked to a type II diabetes-associated phenotype. The polypeptide can include at least one amino acid substitution in the amino acid sequence of SEQ ID NO:23, e.g., an arginine residue substituted at amino acid 18 and/or a valine residue is substituted at amino acid 890 of SEQ ID NO:23. The polynucleotide can have a cytosine residue at nucleotide 2817 of SEQ ID NO:22.
The invention also features a transgenic non-human animal whose genome includes an insulin-degrading polypeptide transgene, wherein the transgene includes a regulatory polynucleotide operably linked to a polynucleotide encoding an insulin-degrading polypeptide, wherein the insulin-degrading polypeptide has an amino acid substitution linked to a type II diabetes-associated phenotype. The animal can be a rat or a mouse.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.